Get Fired Up Over Wood Burning Stoves
by Tom and JoAnne O’Toole
The first heating bill of winter arrives and your eyes widen at the charges. The thermostat is immediately lowered, the family is cautioned about keeping doors and windows closed, and perhaps even encouraged to wear a sweater indoors.
To save yourself this annual anxiety attack, you might give some thought to a secondary heat source to supplement a gas, electric, or oil furnace. Does anyone out there still have a coal furnace?
If you take the time to investigate wood burning stoves you’ll soon develop a respect for their ability to solve the problem of expensive heating costs by using fossil fuels. Most stoves burn short lengths of wood (12-24 inches), and many have strong, quiet blowers, forcing hot air out of upper vents. They can do an excellent job of keeping your home warm and cozy.
Choosing the right stove is the first hurdle. It can get confusing with so many different makes and models on the market.
Of course, the more quality you expect, the more you’ll pay. However, there are a few basic “musts” to consider. Workmanship is important, as well as buying a big enough stove. You can always build a small fire in a big stove, but not the other way around. Make sure your stove has a large, state-of-the-art firebox, and a big loading door that latches tightly.
It’s best to purchase a new stove from a reputable dealer, and make sure it carries a certification of successful testing. Although more expensive, airtight cast iron and plate steel models retain heat longer, and give years of dependable, trouble-free service.
A radiant stove has one main metal shell and the heat from the fire fans out from the unit in all directions. Unfortunately, all directions are not necessarily equally beneficial. For example, heat from the back of the stove will warm the wall, rather than the room.
If you want nostalgia (when folks sat around a potbelly stove at the general store), you’ll find these relics are far from airtight, and burn an excessive amount of wood quickly. These old cast iron workhorses radiate heat, but they need constant attention, and you’re forever emptying the ash box. They are only slightly more practical than burning wood in a fireplace, with most of the heat whooshing up the chimney.
A circulating (convection) stove has an inner combustion chamber, surrounded by an outer shell. A fan expels the hot air between the two metal shells, and the exterior is much cooler than a radiant unit. The flow of heated air is similar to a forced air furnace system, and you’re able to direct the heat more effectively.
What you really want is efficiency in getting the most heat for the least amount of wood and work. The perfect stove would be one that burns the wood completely at the proper temperature, and retains most of the heat inside the structure.
Much of the charm of a wood burning stove is watching the fire itself. Make sure you buy a stove with a self-cleaning glass window in the loading door if you want to watch the fire. Equally important is a stove with convenient, built-in grate and an airtight ash pan.
Manufacturers do make stoves in colors other than the traditional black. If you want a certain color, it’s probably out there somewhere. Some models are even available in a rainbow of enamels.
When positioning your stove, choose a spot where it will be most functional, and locate it so it’s easily observable during operation. The stove must sit on a fire-resistant base, raised from the floor to allow airflow. Because the stove will produce intense radiant heat, you should also consider heat shields on back and sidewalls allowing at least an inch of space away from the walls for ventilation. The minimum distance from an unprotected wall is 36 inches for a radiant-type unit, and 12 inches for a circulating stove. A reflective metal surface will bounce most of the heat off the wall back into the room.
Intense heat has been known to burn a hole through the floor, so noncombustible protection beneath the stove is essential. It should extend beyond the stove at least 12 inches on all sides. If the stove legs are 18 inches or longer, a sheet of reflective metal will do nicely. When the legs are six to 18 inches long, an approved stove board should be placed between the floor and the sheet metal. If the legs are six inches or less use four inches of ventilated blocks or bricks on top of the sheet metal.
(Editor’s Note: The floor and wall protection systems described above are generally used for stoves that do not have UL Listing or the equivalent. Any UL Listed stove should include an owner’s manual that will describe the correct methods to use for floor and wall protection. Always follow the owner’s manual!)
Clearance and venting
Clearances around the stove and piping are critical, as most materials absorb radiant heat, and their combustibility could start a fire.
If you’re concerned about radiant heat, feel the surrounding surfaces with your hands. If they’re hot, you’ve got potential problems, as the heat can “cook” combustible walls and interior wood.
Even fireplace inserts and stoves in fireplaces need careful installation. If you use these heating methods, check your chimney and the surrounding wall. Because the chimney temperatures will be greatly increased, heat is transferred and the surrounding wood can ignite.
Venting your stove is vitally important. The chimney flue should be no more than 25 percent larger than the stovepipe, and never connect more than one heating device to each flue.
Stovepipe connectors must be of the proper gauge recommended by the National Fire Protection Association (NFPA). The pipe should run as straight and short as possible, must not pass through a combustible wall or floor, and cannot be within 18 inches of combustible material (that includes the ceiling).
If you use a prefabricated metal chimney, it should be listed as “residential-type building heating appliance chimney part” by Underwriters Laboratory (UL), or some other recognized testing laboratory. A metal chimney should extend at least three feet above the highest point where it passes through the roof, and at least two feet higher than any portion of the exterior structure within 10 feet.
A stack thermometer helps monitor the temperature of gases leaving the stove. The most and least polluting temperature range is between 200 degree and 400 degrees Fahrenheit. Below 200 degrees the temperature is not sufficient to carry all the unburned, combustible gases in the atmosphere, so they condense along the walls of the stovepipe and chimney as creosote (wood tar) and soot. Above 400 degrees the stove is over heating.
As a state fire marshal suggested to us, “The way you install your stove will determine whether you will live with it or die with it. It isn’t safe until you make is safe.” Safety depends on how you install and use a stove, more so than on the stove itself.
It is essential to keep the chimney clean. Whenever creosote builds up to a fourth of an inch anywhere in the chimney system, it’s time to clean it. The build-up can vary greatly, depending on the wood used, type of fires, frequency of use, and even the stove model. All chimneys should be cleaned at least annually. The most effective and safest method of removing creosote is the regular use of a wire brush that can be pulled through the pipes and up and down the chimney. While you can use chemicals and clean your own chimney, it’s a lot less messy to have a professional chimney sweep do it.
A small hot fire in the stove decreases the amount of creosote and increases the efficiency of the combustion process. Even though the smaller fire means more frequent loading, it’s far safer and produces fewer health problems.
On the other hand, a smoldering fire has heavy creosote potential, and the indoor air pollution also can be increased when a firebox is packed with wood.
Basically the stove is merely a device in which to burn a fire. A good heating unit retains heat and transfers it into the room rather than letting it rush up the chimney. Most good stoves have a firebrick-lined firebox and a baffle plate or secondary heat chamber that makes the heat travel around inside before it exhausts up the chimney.
Gases given off by the burning wood rise from the firebox to the secondary chamber above. If the stove has a catalytic combustion system (a honeycombed device designed to reduce the kindling temperature of the gases), much of the smoke is burned off. This increases the heating capabilities, greatly reduces creosote buildup, and makes the whole operation more pollution-free.
The most efficient stoves are airtight, with the flow of fresh air into the burning area regulated by a damper. You can control the burn. By letting in more air you create a hotter fire. However, with airtight stoves, the combustion of the wood is not always complete because of restricted airflow, but this is the trade-off between controlled heat and a fast, hot burn.
Depending on how sophisticated you want to get, you can have an automatic thermostat to control the damper, holding the temperature constant and helping the fire to burn longer. While this eliminates adjusting the damper, automatic thermostats have been known to cause the damper to stick open, and the stove to overheat.
Keep in mind, no matter how good the stove you buy, and regardless of the option, about the very best you can expect is a stove that’s 50% efficient. That’s a lot better than some of those old, leaky, radiant jobs that are good if they give you 10% efficiency.
Wood species is important
Once you’ve found the stove that’s right for you, give more than just a passing thought to the wood you burn. Different types have different heat values. The heavier or more dense, the higher the heating value. Always burn dry, well-seasoned hardwood. If you buy green wood, it’s essential you season it before using. Green wood has too high moisture content for satisfactory results. Dry wood also helps decrease the amount of creosote build-up.
If you purchase your firewood, you’ll normally not have a choice of tree species. However, you should pay less for wood having a low heating value. Being a knowledgeable firewood buyer will help you get the most for your money.
Depending on your part of the country, high heating value woods include hickory, oak, maple, beech, birch, and dogwood. Soft woods ignite quickly and burn fast, but their heating value is low. Some of these are spruce, aspen (poplar), pine, hemlock, balsam fir, redwood, and basswood.
Seasoned dense wood will burn long and steady, and one cord of such wood is equal to many gallons of fuel oil. A cord of hickory, for example, is equal to 177 gallons, while a cord of soft balsam fir is only equal to burning 96 gallons.
Wood is usually sold by the cord or rick. A standard cord stacked measures four feet wide, four feet high, and eight feet long. A rick is defined as eight feet long, four feet high, but only two feet wide (half a cord). A face cord is generally accepted to be four by eight by one or two feet, or as wide as the lengths of the wood cut.
If someone wants to sell you a “truck load,” it depends on the size of the truck bed. A pick-up truck with a basic four by eight foot bed, 19 inches deep, will only hold a third of a standard cord. If they claim they are selling “about” a cord of wood, and will deliver it in a pick-up, just explain you’ll pay after stacking it, but only for the actual volume you’re receiving.
There are long, long lists of dos and don’ts for wood burning stoves, but some of the more important ones are:
- Use seasoned, dry hard wood.
- Burn short, hot fires, rather than long, smoldering ones.
- Install smoke/heat detectors, and have a good hand fire extinguisher nearby.
- Empty ashes into a metal container with a tight-fitting lid. Keep the container off a combustible floor.
- Don’t burn trash, papers, or small twigs.
- Never use a flammable liquid of any kind to start a fire.
- Never use chemical or starter logs.
- Do not store dry wood near or under the stove. <!–
- Don’t leave the stove burning unattended overnight, or when children are in the house.–>
- Never vent your stove into a flue already used to vent another heating system.
- Do not leave the stove doors open except to fuel the fire.
Before you rush out to buy a wood burning stove, acquaint yourself with the basic information. If you have questions, make a list, and call someone qualified to give you the answers.
Before installing your stove, check with your local building and fire departments of codes regarding clearances, heat shields, venting and chimney connections.
A permit is frequently required for hooking up, and in many instances your dealer will include it. If they don’t install, they’ll usually recommend someone who can do it for you.
With the potential for future fuel shortages, more and more people are looking to wood burning stoves. The risk seems to be that many people have limited experience with these stoves, and fire statistics are much higher than they should be. They show fires are principally caused by improper installation, poor maintenance, and misuse.
Now all this might sound like wood burning stoves are all work and no fun, but that’s not the case. We’ve emphasized proper installation because that’s crucial to eliminate potential risks once the stove is put into use. After all, the first concern must be safety. If it’s done right, then you’re on your way to a season of warmth to say nothing of the rewarding inner glow you’ll have each time you throw another log into the fire.
You can stay toasty warm for as long as Ol’ Man Winter wants to howl and for as long as the wood holds out.
Okay, now that you’re all fired up, start stoking!
Pellet stoves are clean, convenient, economical, and a wonderful innovation. Small though they may be, a pellet stove can produce enough heat for an average size cabin retreat, or small home.
A 40-pound bag of wood pellets into the hopper each morning keeps things cozy. Made from waste sawdust, the pellets look like rabbit food.
A small auger feeds the pellets into the fire, and a draft fan blows the flue gases out, while a blower forces the hot air into the room.
Pellet stoves are very clean burning, and you’ll see very little smoke (if any). Because the pellets are so small, and combustion air is forced around them, efficiency is very high.
These stoves are easy to install, and some models can be converted to burn inexpensive corn. Most stoves are made of light-gauge steel, and are easy to handle. If you are uncomfortable about installing it yourself, perhaps your pellet-stove dealer can lend a hand.
For more information on wood burning stoves write to your state fire marshal, state department of environmental protection, state office of energy resources, or a nearby dealer. Many insurance companies produce well-researched literature on fuel-efficient wood burning stoves, and your agent might be able to help. Locally you can stop at city hall and check with the building department and then seek out your fire department officer in charge of public information.
Copyright Countryside & Small Stock Journal. All rights reserved. Reprinted with permission. Countryside Magazine W11564 Hwy 64 Withee, WI 54498.
Lehman’s does not guarantee the accuracy of this information. Always obey the instructions in your owner’s manual and follow the advice of local safety officials.